RECENT OBSERVATIONS ON THE GONIDIA QUESTION. 116 



A Further Resume of Recent Observations on the 

 '^Gonidia-Question/' By Wm. Archer, M.R.I.A. 



In his critical enumeration of the Lichen-flora of Denmark, 

 Norway, Sweden, and part of Russia, Dr. T. M. Fries^ 

 criticises the remarkable hypothesis of Schwendener as 

 to the nature of lichens, of the literature of which a general 

 resume has lately appeared in these pages.^ As the obser- 

 vations upon this hypothesis by Dr. M tiller^ had escaped 

 being alluded to, it appears advisable, in order to place the 

 matter as fully as possible before the readers of this journal, 

 to give an abstract of them as well as of the conclusions arrived 

 at by Bornet and Treub in recent memoirs, which fully 

 endorse Schwendener's views. 



As will be now widely known, Schwendener's theory sup- 

 poses Lichens to consist of two primarily distinct elements — 

 Algse and Ascomycetes — in such a way that the Algje,or group 

 of algal cells, becoming surrounded and involved, or (more 

 rarely) permeated by the Ascomycete, serve the latter as 

 assimilating host-plant. The two together form the 

 *' Lichen;" hence the former, long known as " gonidia," 

 are not organs of the Lichen, but foreign organisms pressed 

 into its service, and so compelled to lead a new life. 



Fries asks the all-important question, "' In what manner 

 do the gonidia enclosed in the lichen-thalius originate ? " 

 Prof. Schwendener, in his lately published discussion of 

 the subject, argues that no one has observed the develop- 

 ment of the gonidia from terminal cells of the hypha.* How- 

 ever, Dr. Fries asserts that the hypha-branches swell up at 

 the apex, gradually become globular and afterwards filled with 

 green contents. Thxis each becomes eventually a gonidium, 

 which subsequently subdivides. As Dr. Miiller observes, if 

 this were true the Schwendenerian theory would evidently 

 be no longer tenable. Fries does not state in what lichens 

 he had made his observations. However, Miiller refers to a 

 previous observation of his own in Synalissa, bearing out the 

 statement, and showing the gradual formation of gonidia 



1 Eries, ' Lichenographia Scandinavica,' Pars prima, Upsala, 1871. 



2 ' Quart. Journ. Micr. Sc.,' vol. xiii, n. s., p. 217. 



3 ' Flora/ 1872, p. 90. 



* Schwendener : " Erorterungen znr Gonidienfrage," in ' Flora,' May, 

 1872. Translated (in part) in ' Quart. Journ. Micr. Sc.,' vol. xiii, n. s., 

 p. 235. 



